Managing storage pools and volumes

When you configure devices so that the server can use them to store client data, you create storage pools and storage volumes.

About this task

The procedures for configuring devices use the set of defaults that provides for storage pools and volumes. The defaults can work well. However, you might have specific requirements that are not met by the defaults. There are three common reasons to change the defaults:

Optimize and control storage device usage by arranging the storage hierarchy and tuning migration through the hierarchy (next storage pool, migration thresholds).
Reuse tape volumes through reclamation. Reuse is also related to policy and expiration.
Keep a client's files on a minimal number of volumes (collocation).

You can also make other adjustments to tune the server for your systems. See the following sections to learn more. For some quick tips, see Task tips for storage pools.

The examples in topics show how to perform tasks using the Tivoli Storage Manager command-line interface. For information about the commands, see the Administrator's Reference, or issue the HELP command from the command line of a Tivoli Storage Manager administrative client.

Defining storage pools
To optimize data storage, you can specify various properties when you define or update a storage pool using the DEFINE STGPOOL and UPDATE STGPOOL commands.
Task tips for storage pools
Tivoli Storage Manager provides many functions, such as migration and reclamation, for optimizing data-storage operations. To take advantage of these functions, you can create specialized storage pools or specify certain properties in your storage pool definitions.
Managing storage pool volumes
Storage pool volumes are the physical media that are assigned to a storage pool. Storage pool volumes are either random-access or sequential-access, depending on the device type of the device class to which the storage pool is assigned.
Setting up a storage pool hierarchy
To establish a hierarchy, identify the next storage pool, sometimes called the subordinate storage pool. The server migrates data to the next storage pool if the original storage pool is full or unavailable.
Caching in disk storage pools
When cache is enabled, the migration process leaves behind duplicate copies of files after the server migrates these files to the next storage pool in the storage hierarchy. Using cache can improve the speed with which the server retrieves some files. Consider enabling cache for space-managed files that are frequently accessed by clients.
Deduplicating data
Data deduplication is a method for eliminating redundant data in order to reduce the storage that is required to retain the data. Only one instance of the data is retained in a deduplicated storage pool. Other instances of the same data are replaced with a pointer to the retained instance.
Writing data simultaneously to primary, copy, and active-data pools
With Tivoli Storage Manager, you can write data simultaneously to a primary storage pool, copy storage pools, and active-data pools. The simultaneous-write function increases your level of data protection and reduces the amount of time required for storage pool backup.
Keeping client files together using collocation
Collocation reduces the number of volume mounts required when users restore, retrieve, or recall a large number of files from the storage pool. Collocation thus reduces the amount of time required for these operations.
Reclaiming space in sequential-access storage pools
Space on a sequential-access storage volume becomes reclaimable as files expire or are deleted from the volume. Reclamation processing involves consolidating the remaining data from many sequential-access volumes onto fewer new sequential-access volumes.
Estimating space needs for storage pools
Three default random-access disk storage pools are provided at installation. You can add space to these storage pools by adding volumes, or you can define additional storage pools.
Monitoring storage-pool and volume usage
Monitor your storage pools and volumes to determine space requirements, the status of data migration from one to storage pool to the next storage pool in the storage hierarchy, and the use of disk space by cached copies of files that have been migrated to the next storage pool.
Moving data from one volume to another volume
You might need to move data in some situations, for example, when you need to salvage readable data from a damaged volume. To move data (files) from one volume to another volume in the same or a different storage pool, use the MOVE DATA command. The volumes can be onsite volumes or off-site volumes.
Moving data belonging to a client node
You can move data in a sequential-access storage pool for one or more nodes, or for a single node with selected file spaces, using the MOVE NODEDATA command. The data can be in either a primary storage pool, copy storage pool, or active-data pool.
Renaming storage pools
When you distribute policy using enterprise configuration, you might need to rename a storage pool. Renaming a storage pool can require changing the destination storage pool in copy groups and management classes.
Defining copy storage pools and active-data pools
Use a copy storage pool or an active-data pool to back up one or more primary storage pools. When you definecopy storage pools or active-data pools, you can take advantage of various Tivoli Storage Manager functions by specifying certain properties.
Deleting storage pools
Before deleting a storage pool, you need to take certain precautions to prevent data loss and to ensure uninterrupted storage operations.
Deleting storage pool volumes
You can delete empty storage pool volumes or volumes that contain data from primary storage pools, copy storage pools, or active-data pools. You can also delete the client files that those volumes contain.